Relay control system



y 29, 1952 E. A. HESTER 2,605,309

RELAY CONTROL SYSTEM Filed April 14; 1950 9 I 10 IO 7 I Feeder 5L-hLStofion I Breaker 55 g 3 Subs Teflon l4 l4 l4 l4 l4 l4 Fig.l

Fig.2.

WITNESSES: INVENTOR Edgar A Hester.

Patented July 29, 1952 UNITED STATES PATENT OFFICE aeoasos RELAY CONTROLSYSTEM Edgar A. Hester, Pittsburgh, Pa., assignor to WestinghouseElectric Corporation, East Pittsburgh, Pa., a-corporation ofPennsylvania Application April 14, 1950, Serial No. 155,818

4 Claims.

The invention relates to electrical distribution If for any reason thesubstation circuit breaker is opened with all of the services or loadsconnected to the feeder, and the breaker remains open for half an hour,for example, all the motors connected to the feeder get set in theirstarting position. Reclosure of the station breaker therefore places aheavy overload on the feeder since the starting current of the motorsmay be from seven to ten times their running current. This excessiveload will trip the substation breaker, and prevent it from remainingclosed. It is then necessary to go out and cut the branch circuits fromthe feeder until the load is reduced to a point where the stationbreaker will remain closed. The branch circuits may then successively bereconnected to the feeder.

'It is an object of the present invention to provide an improved relaysystem for controlling the connection of the branch circuits to thefeeder circuit of a distribution system in such a manner that upon afailure in voltage on the feeder circuit, all of the branch circuitswill be disconnected, and upon a resumption of voltage on the feedercircuit, the branch circuits are reclosed in spaced timed relation sothat the,

total load of all of the branch circuits is gradually picked up. Thisavoids an undue current load through the substation breaker.

It is also an object of the invention to provide an improvedvoltage-responsive circuitbreaker system and an improved time-delayrelay which is usable in such system.

Other objects of the invention. will become apparent from the followingdescription read in connection with the accompanying drawing, in which:

Figure 1 is a schematic view of a distribution circuit to which myinvention is applicable;

Fig. 2 is a schematic view of a circuit breaker control device andsystem usable in the system of my invention; and

Fig. 3 is a schematic view of a time-delay voltage-responsive relaywhich may be used in connection with the invention.

Referring to Figure 1, a feeder circuit 5 is energized through asubstation circuit breaker which is fed from the substation bus 9. Thebreaker 1 is provided with overload protection in accordance withusualpractice. Various loads l0 may be connected direct to the feedercircuit, and in addition there are usually a number of branch or loadcircuits l I connected to the feeder 5 through circuit breakers l3. Itis understood that loads M, which may be lamps, motors or otherappliances, are variously connected to the lead circuits ll.

Disregarding the load circuit breakers l3, it should be apparent that ifthe substation breaker 1 is reclosed after it has been opened for anyreason, a reenergization of all the connected load on the systemwillresult in a substantial current surge through the substation breakerwhich would promptly reopen it under the influence of its overload-tripcontrol.

In order to avoid this difficulty, each of the circuit breakers I3 isprovided with a control as indicated in Fig. 2. This comprises(schematically) a circuit breaker movable contact H which is operateddirectly by the floating end of a flyball mechanism 20, the rotation ofwhich is controlled by a motor 22. The motor 22 may be of any sizesuitable for operating the flyball and contact operating mechanism. Thearrangement is such that when the motor 22 is in operation the flyballs24 will be extended to the position shown in Fig. 2, with the lower end26 of the flyball assembly in a raised position and the link 28maintainingthe circuit breaker contact I! in closed position. Upondeenergization of the motor 22, the flyballs 24 retract, under theinfluence of a spring 25, if desired, with cause the dropping of thelower part 26 of the assembly and consequent movement of the link 8 toopen the contact H. The link 28 of course may be pivotally secured to acollar 29 freely rotatable with respect to the flyball portion 26.

A pallet switch 30 is operated by a link 32 to bridge a pair of contacts34 when the motor 22 is energized, and upon the collapse of the flyballmechanism the pallet switch bridges contacts 36, for a purpose to bedescribed.

Energization of motor 22 from the feeder circuit 5 may be obtained bymeans of a potential transformer 38, one side of the secondary thereofextending through the winding of the motor 22, the pallet switchcontacts 34 and conductor 40 to the other side of the transformersecondary. So long, therefore, as there is voltage on the feeder 5, themotor 22 continues to rotate with the fiyballs 24 in the position shownin Fig. 2, and the circuit breaker contact I! is maintained closed. If,however, the voltage on feeder fails, the motor 22 is deenergized andthe fiyballs 24 retract. Accordingly, the portion 26 of the flyballassembly starts to drop and carries with it the end of link 28 whichopens the circuit breaker contacts IT.

The motor, of course, slows gradually and its inertia, as well as thatof the flyballs, provides an inherent time-limit which can bepredetermined by the construction of the parts to be such that in theevent of only momentary loss of voltage on the feeder 5, the motor 22will again be energized to bring the parts back into the position shownwithout opening the circuit breaker contact [1. Of course, if desired, agreater time element may be provided by using a dashpot 42 to give alonger delay to the opening of contacts I! to take care of momentaryvoltage loss of greater periods of time without interruption of the loadcircuit.

However, upon the occurrence of a low voltage condition on the feederwhich exists for .a predetermined time, the breaker contact I! will beopen. The pallet'switch.3034 will open thereby breaking the circuit ofthe motor 22, and the pallet switch 38 will bridge its lower contacts35.

'When voltage is ireestablished on the feeder 5, it is desired toreclose the breaker contact H, and this is accomplished by means of asmall timing motor 44 which operates, through suitable gearing, acontact arm 46 in the path of rotation of which is disposed a contactsegment 48. The motor '44 is connected, as indicated, from one side ofthe transformer secondary through the winding of the motor, the lowercontacts '36 of the pallet switch 30, back to the other side of thetransformer secondary. The motor 44 swings the contact arm 46 in apredetermined length of time into engagement'with contact segment 48which establishes a circuit to motor 22 through the contact arm 46,segment 48. The motor 22 being reenergized causes the raising of thefiyball assembly portion 26 and as it comes up to the position showncauses the closure of the circuit-breaker contact [1. In such movementthe lower contacts '36 of the pallet switch 30 are opened, therebydeenergizing the timing motor 44. However, it is preferred that a secondcontact segment 50 be provided which establishes a circuit through thetiming motor 44, the segment 50, contact arm '46, upper pallet switchcontacts 34 to conductor 40 inthe transformer secondary circuit.Accordingly, the timing motor will continue to operate until the arm 46rides over segment '50,'whereupon it will be deenergized with the switcharm '46 in its initial position.

In the above-described structure, the "motor and flyball mechanismcontrol the circuit breaker contacts directly. However, it is within thecontemplation of the invention that the motor and flyball assembly maybe used to control contacts 52, 54 and 56 (Fig. 3) to energize thetripping and reclosing coils of a circuit breaker. This has theadvantage of permitting the use of a motor 22' of substantially smallersize and capacity than the motor 22 in Fig. 1.

It is quite apparent that modifications may be made in the system andconstruction shown without departing from the spirit of the invention asset forth in the appended claims.

I claim as my invention:

1. In a distribution system including a feeder circuit, a plurality ofbranch circuits and circuit breakers for controlling the individualconnection of said branch circuits to said feeder circuit, controlmeansfor said circuit breakers including time-delayed means responsive to adrop in feeder circuit voltage of a predetermined amount and for apredetermined period to open the associated breaker, and meansresponsive to a return of operating voltage on said feeder to close saidassociated breaker with a predetermined time delay.

2. In a distribution system including a feeder circuit, a plurality ofbranch circuits and circuit breakers for controlling the individualconnection of said branch circuits to said feeder circuit, control meansfor said circuit breakers including time-delayed means responsive toadrop in feeder circuit voltage to open the associated breaker after apredetermined time delay, and means responsive to a return of operatingvoltage .on 'said feeder'to close said associated breaker-with apredetermined time delay.

3. In an electrical distribution system including a feeder circuit and aplurality of load circuits to be energized therefrom, circuit breakersfor controlling the connections of said feeder'and load circuits,control means for each of said breakers responsive to loss of voltage onsaid feeder to open said breakers with a time delay, and means forreclosing said breakers in response to reenergization of said feederincluding a timing device responsive to feeder voltage for controllingsuch reclosure, the timing devices of the individual breakers being setto control the reclosure of the associated breaker at different timeintervals.

4. In an electrical distribution system including a supply circuit, aload circuit and a circuit breaker for controlling the connectiontherebetween, means responsive to a loss of voltage on said feeder toopen said breaker comprising an electric motor energized by said feederand inertia means responsive to the speed of rotation thereof foropening said'breaker when such speed decreases a'predetermined amount.

EDGAR A. HES'I'ER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,272,444 Holliday Jul-y 16, 19181,272,447 Jacobs July 16, 1918

